Microstructure and electrical properties of porous Y1-xCaxFeO3 cathode materials by gelcasting process

Porous Y1-xCaxFeO3 (YCF) ceramics were successfully fabricated by a gelcasting process followed by sintering the gelled mixture of Y2O3, CaCO3 and Fe2O3. A pure YCF ceramic was obtained when the gelcast with x less than or equal to 0.10 was calcined at 1250 degreesC in air for 5 h. Results showed that the specimen with x = 0.10 had the lowest porosity. This contributed to the formation of a solid solution, which might greatly facilitate the sintering process of specimens. The Y0.9Ca0.1FeO3 specimens calcined at 1200-1275 degreesC for 5 h have an open porosity of 66,2-16.4% and mean pore size of 1.91 -0.69 mum. The electrical conductivity of the porous specimens was investigated by the DC four-probe method. The results showed that Ca2- doping greatly improves the conductivity of YCF specimen and dramatically reduces the activation energy for conductivity. (C) 2002 Elsevier Science B.V. All rights reserved.